U.S. patent application number 12/840408 was filed with the patent office on 2011-05-12 for method for making carbon nanotube film.
This patent application is currently assigned to TSINGHUA UNIVERSITY. Invention is credited to SHOU-SHAN FAN, QUN-QING LI, JING XIE, GANG ZHENG.
Application Number | 20110109006 12/840408 |
Document ID | / |
Family ID | 43955296 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110109006 |
Kind Code |
A1 |
ZHENG; GANG ; et
al. |
May 12, 2011 |
METHOD FOR MAKING CARBON NANOTUBE FILM
Abstract
A method for making a carbon nanotube film is provided. First, a
carbon nanotube array is formed on a grown substrate. The carbon
nanotube array is pressed with a first substrate using a first
pressing force to form a carbon nanotube film precursor. Then the
first substrate and the grown substrate are separated, and the
carbon nanotube film precursor is transferred onto the first
substrate. After that, the carbon nanotube film precursor is
pressed using a second substrate with a second pressing force.
Lastly, the first substrate and the second substrate is separated,
with part of the carbon nanotube precursor transferred to the
second substrate to form the carbon nanotube film.
Inventors: |
ZHENG; GANG; (Beijing,
CN) ; LI; QUN-QING; (Beijing, CN) ; XIE;
JING; (Beijing, CN) ; FAN; SHOU-SHAN;
(Beijing, CN) |
Assignee: |
TSINGHUA UNIVERSITY
Beijing
CN
HON HAI PRECISION INDUSTRY CO., LTD.
Tu-Cheng
TW
|
Family ID: |
43955296 |
Appl. No.: |
12/840408 |
Filed: |
July 21, 2010 |
Current U.S.
Class: |
264/112 ;
977/847 |
Current CPC
Class: |
C23C 16/26 20130101;
H01L 51/0013 20130101; C01B 32/16 20170801; H01L 51/0048 20130101;
B82Y 10/00 20130101; B82Y 30/00 20130101; C23C 16/01 20130101; H01L
51/0508 20130101; B82Y 40/00 20130101 |
Class at
Publication: |
264/112 ;
977/847 |
International
Class: |
B27N 3/02 20060101
B27N003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2009 |
CN |
200910110046.8 |
Claims
1. A method for making a carbon nanotube film comprising the
following steps: providing a carbon nanotube array formed on a
grown substrate; pressing the carbon nanotube array with a first
substrate using a first pressing force to form a carbon nanotube
film precursor; separating the first substrate and the grown
substrate, and transferring the carbon nanotube film precursor onto
the first substrate; pressing the carbon nanotube film precursor
using a second substrate with a second pressing force; and
separating the first substrate and the second substrate, and
transferring part of the carbon nanotube film precursor to the
second substrate to form a carbon nanotube film.
2. The method of claim 1, wherein the carbon nanotube array is
formed by the following sub-steps: providing a grown substrate;
forming a catalyst layer on the grown substrate; annealing the
grown substrate with the catalyst layer; heating the annealed
substrate in a furnace filled with a protective gas; and supplying
a mixture of a protecting gas and a carbon source gas in the
furnace, thereby growing the carbon nanotube array.
3. The method of claim 1, wherein the carbon nanotube array
comprises a plurality of carbon nanotubes forming a plurality of
strips, a distance between adjacent strips in a range from about 10
micrometers to about 1 millimeter.
4. The method of claim 3, wherein each strip forms one carbon
nanotube film.
5. The method of claim 1, wherein the first pressing force is
maintained longer than about 5 seconds.
6. The method of claim 1, wherein the first pressing force is in a
range from about 10 MPa to about 15 MPa.
7. The method of claim 1, wherein the first pressing force is
applied along a first direction, an angle .alpha. formed between
the first direction of the first pressing force and the grown
substrate is from 0.degree. to about 90.degree..
8. The method of claim 7, wherein the angle .alpha. is about
90.degree., and the carbon nanotube film precursor comprises a
plurality carbon nanotubes isotropically disposed.
9. The method of claim 1, wherein a combined force between the
first substrate is greater than a combined force between the carbon
nanotube array and the grown substrate.
10. The method of claim 9, wherein the carbon nanotube precursor
comprises a plurality of carbon nanotubes joined with each other by
Van der Waals attractive force, and the Van der Waals attractive
force is greater than the combined force between the carbon
nanotube array and the grown substrate.
11. The method of claim 10, wherein a combined force between the
first substrate and the carbon nanotube precursor is larger than
the Van der Waals attractive force between the carbon nanotubes,
and is less than or equal to a combined force between the second
substrate and the carbon nanotube precursor.
12. The method of claim 1, wherein a material of the first
substrate or the second substrate is polyethylene terephthalate,
polydimethylsiloxane, polypropylene, polyvinyl chloride,
polyethylene, polystyrene or polyethylene terephthalate.
13. The method of claim 1, wherein the second pressing force is
less than the first pressing force, the second pressing force is in
a range from about 3 MPa to about 8 MPa.
14. The apparatus of claim 1, wherein a thickness of the carbon
nanotube film is in a range from about 50 nanometers to about 1
micrometer.
15. The method of claim 1, further comprising putting the carbon
nanotube film and the second substrate in a solvent to wash the
carbon nanotube film.
16. The method of claim 1, further comprising providing a polymer
in a liquid state and applying the polymer on a top of the carbon
nanotube array before pressing the carbon nanotube array with the
first substrate.
17. The method of claim 16, wherein a polymer layer is formed on
the top surface of the carbon nanotube array after the liquid
polymer is applied on the top surface, and the first substrate is
physically contacting the polymer layer.
18. The method of claim 16, wherein the carbon nanotube array
comprises a plurality of carbon nanotubes, gaps are formed between
the carbon nanotubes, and the liquid polymer is disposed in the
gaps.
19. The method of claim 16, wherein a combined force between the
polymer layer and the first substrate is larger than a combined
force between the carbon nanotube film precursor and the grown
substrate, and a combined force between the polymer layer and the
carbon nanotube array is larger than the combined force between the
carbon nanotube film precursor and the grown substrate.
20. The method of claim 16, wherein the material of the polymer is
selected from the group consisting of epoxy resin, bismaleimide
resin, cyanate ester resin, silicone rubber, polydimethylsiloxane,
PMMA, polypropylene, polyethylene, polyvinyl alcohol, and
polymethacrylate resin.
Description
RELATED APPLICATIONS
[0001] This application claims all benefits accruing under 35
U.S.C. .sctn.119 from China Patent Application No. 200910110046.8,
filed on Nov. 6, 2009 in the China Intellectual Property Office,
the disclosure of which is incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure generally relates to a method for
transfer-printing carbon nanotube film.
[0004] 2. Description of Related Art
[0005] Carbon nanotubes (CNT) are a carbonaceous material and have
received much interest since the early 1990s. Carbon nanotubes have
interesting and potentially useful electrical and mechanical
properties. Due to these and other properties, CNTs have become a
significant focus of research and development for use in electron
emitting devices, sensors, and transistors, among other
devices.
[0006] Generally, the carbon nanotubes, prepared by conventional
methods, are in particle or powder form. The particle/powder-shaped
carbon nanotubes limit the number of applications. Thus,
preparation of macroscopic carbon nanotube structures has attracted
lots of attention.
[0007] Carbon nanotube film is one important macroscopic carbon
nanotube structure and can be used in a thin film transistor (TFT).
Carbon nanotube film can be made by methods using carbon nanotube
powders, such as a dropping and drying solvent method, a
Langmuir-Blodgett (L-B) method, a printing method, an
electrophoresis method, or a membrane filter method. However, the
above-described methods generally have complicated fabrication
procedures.
[0008] What is needed, therefore, is a method for making a carbon
nanotube film which can overcome the disadvantages discussed
above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Many aspects of the embodiments can be better understood
with reference to the following drawings. The components in the
drawings are not necessarily drawn to scale, the emphasis instead
being placed upon clearly illustrating the principles of the
embodiments. Moreover, in the drawings, like reference numerals
designate corresponding parts throughout the several views.
[0010] FIG. 1 is a flow chart of one embodiment of a method for
making a carbon nanotube film.
[0011] FIG. 2 is a process chart showing the steps of the method of
FIG. 1 for making the carbon nanotube film.
DETAILED DESCRIPTION
[0012] The disclosure is illustrated by way of example and not by
way of limitation in the figures of the accompanying drawings in
which like references indicate similar elements. It should be noted
that references to "an" or "one" embodiment in this disclosure are
not necessarily to the same embodiment, and such references mean at
least one.
[0013] Referring to FIG. 1 and FIG. 2, one embodiment of a method
for producing a carbon nanotube film includes the following
steps:
[0014] (S1) providing a carbon nanotube array 10 formed on a grown
substrate 20;
[0015] (S2) pressing the carbon nanotube array 10 with a first
substrate 30 using a first pressing force to form a carbon nanotube
film precursor 40;
[0016] (S3) separating the first substrate 30 and the grown
substrate 20, and transferring the carbon nanotube film precursor
40 onto the first substrate 30;
[0017] (S4) pressing the carbon nanotube film precursor 40 using a
second substrate 50 with a second pressing force; and
[0018] (S5) separating the first substrate 30 and the second
substrate 50, and transferring part of the carbon nanotube
precursor 40 onto the second substrate 50 to form at least one
carbon nanotube film 60.
[0019] In step (S1), the carbon nanotube array 10 can be formed by
the steps of:
[0020] (a1) providing the grown substrate 20;
[0021] (a2) forming a catalyst layer on the grown substrate 20;
[0022] (a3) annealing the grown substrate 20 with the catalyst
layer;
[0023] (a4) heating the annealed grow substrate 20 in a furnace
filled with a protective gas; and
[0024] (a5) supplying a mixture of a protecting gas and a carbon
source gas in the furnace, thereby growing the carbon nanotube
array 10.
[0025] In step (S1), the carbon nanotube array 10 includes a
plurality of carbon nanotubes substantially parallel to each other
and approximately perpendicular to the grown substrate 20. The
carbon nanotube array 10 includes a first end surface 12 and a
second end surface 14. Once the carbon nanotube array 10 is formed
on the grown substrate 20, the second end surface 14 of the carbon
nanotube array 10 is connected to a top surface of the grown
substrate 20, and the carbon nanotubes in the carbon nanotube array
10 extend approximately perpendicularly away from the top surface
of the grown substrate 20. A material of the grown substrate 20 can
be silicon or silicon dioxide. In one embodiment, the material of
the grown substrate 20 is silicon. Alternatively, in another
embodiment, some of the carbon nanotubes in the carbon nanotube
array 10 can be removed to form a pattern in the carbon nanotube
array 10. For example, after some of the carbon nanotubes are
removed, the other carbon nanotubes in the carbon nanotube array 10
form a plurality of strips. Each of the strips includes a plurality
of carbon nanotubes substantially perpendicular to the grown
substrate 20. A distance between the adjacent strips can be in a
range from about 10 micrometers to about 1 millimeter.
[0026] In step (S2), the first substrate 30 will contact the first
end surface 12 of the carbon nanotube array 10. A material of the
first substrate 30 is not limited, although a combined force
between the carbon nanotube film precursor 40 and the first
substrate 30 must be greater than a combined force between the
carbon nanotube array 10 and the grown substrate 20. A material of
the first substrate 30 can be polyethylene terephthalate (PET),
polydimethylsiloxane, polypropylene, polyvinyl chloride (PVC),
polyethylene, polystyrene or polyethylene terephthalate (PBT). In
one embodiment, the material of the first substrate 30 is PET.
[0027] In step (S2), the first pressing force is applied along a
first direction L1. An angle .alpha. can be formed between the
first direction L1 of the first pressing force and the grown
substrate 20, such that 0.degree.<.alpha..ltoreq.90.degree.. In
one embodiment, .alpha. is about 90.degree.. The first pressing
force can be larger than 1 MPa. For example, the first pressing
force can be in a range from about 10 MPa to about 15 MPa. The
first pressing force will be maintained longer than about 5
seconds. In one embodiment, it is longer than about 60 seconds.
After being pressed by the first pressing force, the carbon
nanotubes in the carbon nanotube array 10 is compressed onto the
grown substrate 20 to form the carbon nanotube film precursor 40.
The carbon nanotube film precursor 40 contacts and combines closely
with the first substrate 30. An orientation direction of the carbon
nanotubes in the carbon nanotube precursor 40 is determined by the
first direction L1. If the angle .alpha. is about 90.degree., the
carbon nanotubes will be isotropically disposed. If the angle
.alpha. is less than about 90.degree., that is to say, the first
pressing force has a horizontal force component, the carbon
nanotubes will be oriented along a direction of the horizontal
force component. The carbon nanotubes are overlapped with each
other and joined with each other by Van der Waals attractive force
in the carbon nanotube film precursor 40. The Van der Waals
attractive force between the carbon nanotubes can be larger than
the combined force between the grown substrate 20 and the carbon
nanotube film precursor 40. A thickness of the carbon nanotube film
precursor 40 can be in a range from about 20 micrometers to about
30 micrometers.
[0028] In step (S3), the combined force between the carbon nanotube
film precursor 40 and the first substrate 30 is greater than the
combined force between the carbon nanotube film precursor 40 and
the grown substrate 20. Thus, after separating the grown substrate
20 and the first substrate 30, the carbon nanotube film precursor
40 will be attached on a surface of the first substrate 30.
[0029] In step (S4), a material of the second substrate 50 can be
polyethylene terephthalate, polydimethylsiloxane, polypropylene,
polyvinyl chloride, polyethylene, polystyrene or polyethylene
terephthalate. The material of the second substrate 50 can be the
same as the material of the first substrate 30. In one embodiment,
the material of the second substrate 50 is PET.
[0030] In step (S4), the carbon nanotube precursor 40 has a first
surface (not labeled) and a second surface (not labeled) opposite
to the first surface. The first surface is physically contacting
with the first substrate 30, and the second surface is physically
contacting with the second substrate 50. Because the carbon
nanotubes in the carbon nanotube precursor 40 are overlapped with
each other, some carbon nanotubes are contacting and combined with
the first substrate 30, some carbon nanotubes are contacting and
combined with the second substrate 50, and the rest of the carbon
nanotubes are contacting neither the first substrate 30 nor the
second substrate 50. The carbon nanotubes contacting neither the
first substrate 30 nor the second substrate 50 are disposed in the
middle portion of the carbon nanotube film precursor 40. The
combined force between the carbon nanotube film precursor 40 and
the first substrate 30 is larger than the Van der Waals attractive
force between the carbon nanotubes.
[0031] In step (S4), the second pressing force is less than the
first pressing force, and can be larger than 1 MPa, for example,
the second pressing force can be in a range from about 3 MPa to
about 8 MPa. The second pressing force will be maintained longer
than about 5 seconds. In one embodiment, it is longer than about 60
seconds.
[0032] In step (S5), because the combined force between the first
substrate 30 and the carbon nanotube precursor 40 is larger than
the Van der Waals attractive force between the carbon nanotubes,
and is less than or equal to the combining force between the second
substrate 50 and the carbon nanotube precursor 40. The carbon
nanotube precursor 40 will be separated into two parts when the
first substrate 30 and the second substrate 50 are separated from
each other. The carbon nanotubes contacting and combining with the
first substrate 30 will be attached on the first substrate 30, and
the carbon nanotubes that are contacting and combining with the
second substrate 50 will be attached on the second substrate 50.
The second surface of the carbon nanotube film precursor 40 will be
attached on the second substrate 50 after the first substrate 30
and the second substrate 50 are separated. The carbon nanotubes
attached on the second substrate 50 form the carbon nanotube film
60. A thickness of the carbon nanotube film 60 can be in a range
from about 50 nanometers to about 1 micrometer. In one embodiment,
if the carbon nanotubes in the carbon nanotube array 10 form the
plurality of strips, a plurality of carbon nanotube films will be
formed on the second substrate 50. Because the second substrate 50
is transparent PET, the plurality of carbon nanotube films and the
substrate 50 can be used to make a TFT.
[0033] Alternatively, the carbon nanotube film 60 can be soaked in
a liquid to decrease the thickness of the carbon nanotube film 60.
In one embodiment, the carbon nanotube film 60 and the second
substrate 50 can be washed in an acetone solvent. The carbon
nanotube film 60 and the second substrate 50 are put in the acetone
solvent and are bombarded with ultrasonic pulses for about 10
minutes, so the thickness of the carbon nanotube film can be less
than 50 nanometers. Thus, the method of making the carbon nanotube
film 60 is simple.
[0034] In another embodiment, a method for producing a carbon
nanotube film includes the following steps:
[0035] (M1) providing a carbon nanotube array having a first end
surface and a second end surface formed on a grown substrate, the
second end surface is physically contacting with the grown
substrate;
[0036] (M2) providing a polymer in a liquid state, and applying the
polymer on the carbon nanotube array from the first surface;
[0037] (M3) pressing the carbon nanotube array with a first
substrate using a first pressing force to form a carbon nanotube
film precursor;
[0038] (M4) separating the first substrate and the grown substrate,
and transferring the carbon nanotube film precursor onto the first
substrate;
[0039] (M5) pressing the carbon nanotube film precursor using a
second substrate with a second pressing force; and
[0040] (M6) separating the first substrate and the second
substrate, part of the carbon nanotube precursor is transferred to
the second substrate to form at least one carbon nanotube film.
[0041] The detailed process of M1 can be the same as the step S1
discussed above.
[0042] In step (M2), the polymer material can be thermoplastic
polymer or thermosetting polymer. The thermosetting material can be
selected from epoxy resin, bismaleimide resin, cyanate ester resin,
silicone rubber, polydimethylsiloxane, or PMMA. The thermoplastic
material can be selected from polypropylene, polyethylene,
polyvinyl alcohol, or polymethacrylate resin. The polymer in liquid
state can be applied on the second surface of the carbon nanotube
array by a coating method, spraying method, or dropping method. The
polymer can be heated to a liquid state. The carbon nanotube array
includes a plurality of carbon nanotubes, with gaps formed between
the carbon nanotubes. As such, some of the liquid polymer will
collect in these gaps. A polymer layer can be formed on the first
surface of the carbon nanotube array after the liquid polymer is
applied on the first surface. In one embodiment, the polymer layer
can be solidified.
[0043] In step (M3), the first substrate will contact with the
polymer layer. In addition, a combined force between the polymer
layer and the first substrate is larger than a combined force
between the carbon nanotube film precursor and the grown substrate.
A combined force between the polymer layer and the carbon nanotube
array is larger than the combined force between the carbon nanotube
film precursor and the grown substrate. If the polymer is still in
a liquid state, after pressing with the first substrate, the liquid
polymer will infiltrate into the carbon nanotube array, so that the
carbon nanotube film precursor becomes a composite structure. The
other detailed process in step (M3) is similar to step (S2)
disclosed above.
[0044] The detailed process of M4 is similar to step S3 discussed
above.
[0045] The detailed process of M5 is similar to step S4 discussed
above.
[0046] The detailed process of M6 is similar to step S5 discussed
above.
[0047] It is to be understood that the above-described embodiments
are intended to illustrate rather than limit the disclosure.
Variations may be made to the embodiments without departing from
the spirit of the embodiments as claimed. The above-described
embodiments illustrate, but do not restrict the scope of the
disclosure.
[0048] Depending on the embodiment, certain of the steps of methods
described may be removed, others may be added, and the sequence of
steps may be altered. It is also to be understood that the
description and the claims drawn to a method may include some
indication in reference to certain steps. However, the indication
used is only to be viewed for identification purposes and not as a
suggestion as to an order for the steps.
* * * * *